The invention relates to improvements in methods of and in machines for treating webs of photographic material, such as photographic roll films and photographic paper.
Exposed photographic films, especially color films, just be developed in such a way that each and every increment of the film is treated for a predetermined interval of time. This is particularly important in connection with the treatment of exposed films in the developing and fixing baths of the developing machine, especially in the developing bath. The quality of developed images is adversely affected not only if the interval of treatment in the developing bath is too short but also if the duration of treatment exceeds a predetermined optimum interval. Therefore, presently known developing machines are designed in such a way that the developing tank contains a predetermined quantity of developing solution and the film is transported through the bath along a path of predetermined length and at a predetermined speed. This ensures that each and every increment of the film is contacted by the developing solution for a desired interval of time.
A drawback of conventional developing machines which are capable of ensuring that each and every increment of an exposed film will be contacted by developing solution for an optimum interval of time is that they cannot be directly coupled to other machines in a photographic processing laboratory or in a like establishment. The reason is that the machine or machines which precede the developing machine cannot always deliver films at a speed which is required during transport of films through the developing, fixing and rinsing baths of a standard developing machine for color photographic films. For example, if the developing machine is to receive a very long web which is obtained by splicing a large number of exposed photographic roll films end-to-end, the speed of the web at the outlet of the splicing machine often fluctuates within a rather wide range. Therefore, it is customary to confine the long web of spliced-together photographic roll films in a light-tight cassette and to deliver the cassette to the developing machine where the web is drawn from the cassette at a constant speed which is required to guarantee that each and every increment of the web will be treated (at least in the developing tank) for a predetermined interval of time. The developed web is convoluted on the core of a reel and is transferred into a copying machine where the images of film frames are copied on photographic paper. The photographic paper is thereupon developed in a separate developing machine and is subdivided into prints which are confined in envelopes, together with sections of corresponding films, for shipment or delivery to dealers in photographic materials and cameras or directly to customers.
The total period of time which is taken up for splicing discrete exposed roll films end-to-end, for confining the resulting web in a cassette, for transferring the cassette to a developing machine, for developing the web, and for collecting the developed web on a reel is a multiple of the period of time which elapses while the films and the web are advanced in the splicing machine and the web is advanced in the developing machine. The splicing machine normally comprises or is combined with means for automatically removing exposed but undeveloped customer films from their cartridges, for trimming the leaders of discrete films, for separating the trailing ends of films from cartridges, for discarding the cartridges, for advancing the leaders of successive trimmed and separated films to the splicing station into proper position with reference to the trailing end of the growing web of spliced-together films, for splicing the leaders to the adjacent trailing end of the web, and for confining the web in a lighttightly sealed cassette for transport to the developing machine. In the developing machine, the leader of a web which is confined in the cassette is attached to a band which serves to thread the leader through the baths and through the drying unit of the developing machine. It is also known to attach the leader of a fresh web directly to the trailing end of the preceding web of spliced-together photographic roll films.
If the films which are spliced together to form a web are not provided with notches in predetermined positions relative to the film frame, the developing machine is followed by a notching machine which provides the web with at least one notch for each film frame in order to ensure proper positioning of film frames with reference to the copying instrumentalities in the printer which images the frames onto photographic paper. In addition, the notches serve to ensure proper subdivision of exposed and developed films into sections of optimum length, e.g., into sections each of which contains four or six film frames, which can be readily inserted into standard customer envelopes together with the respective prints.
It is a well known fact that the overall period of time which is required to process a customer film, starting with removal of the film from its cartridge and ending with insertion of film sections and corresponding prints into the pockets of a customer envelope, is a multiple of that period of time during which the films and the corresponding lengths of photographic paper are actually treated, i.e., withdrawn from cartridges, spliced together with other customer films, developed, copied, subdivided and introduced into envelopes. An acceleration of the processing operation by placing a developing machine for exposed customer films and/or a developing machine for photographic paper in line with other machines, such as a splicing machine for customer films and a printer for transfer of images of exposed and developed film frames onto photographic paper, is not possible in view of the aforediscussed mode of operation of presently known developing machines, namely in view of the need to transport a web of coherent customer films or a long web of photographic paper at a fixed speed.
Attempts to assemble one or more developing machines with one or more other machines which are needed in connection with the processing of customer films include the provision of large magazines which are installed ahead of the developing machines and are designed to store considerable lengths of exposed but undeveloped photographic material so as to compensate for eventual fluctuations of the outputs of machines which precede the developing machines. Such proposals have met with limited success because a large variable-capacity magazine is expensive and takes up much space. In addition, each magazine must be designed to prevent penetration of any light since it serves to store undeveloped photographic films or undeveloped photographic paper. Moreover, each magazine causes a pronounced lengthening of the path for transport of photographic material. Additional time is lost when a photographic processing laboratory or a similar establishment employs lengths of flexible band material which is used to thread the leaders of webs of spliced-together photographic films or the leaders of webs of photographic paper through the respective magazines. In addition, the utilization of such bands necessitates the provision of additional storing, advancing and splicing facilities which contribute to the bulk and cost of the developing and other processing operations even though the cost of bands is much less than the cost of photographic roll films. As a rule, the width of such bands matches the width of films or the width of photographic paper.
Commonly owned German Pat. No. 23 53 601 to Pfeifer et al. discloses a developing machine wherein the tank for a supply of treating liquid has advancing rolls at the inlet, advancing rolls at the outlet, and guide elements which direct the leader of a web of exposed but undeveloped photographic material from the advancing rolls at the inlet toward the advancing rolls at the outlet. Once the leader reaches the outlet, the guide elements are retracted and the web is caused to form a loop by gravity. By appropriate selection of the speed of the web and by appropriate selection of the size of the looped portion of the web between the inlet and the outlet, the developing machines of Pfeifer et al. ensures that each increment of the web is treated for a predetermined interval of time. A drawback of the patented developing machine is that it cannot be directly coupled to one or more other machines except by the provision of a large variable-capacity magazine for temporary storage of the web ahead of the inlet to the tank.